Filariasis



Filariasis





Filariasis is a parasitic infection that is classified according to the body cavity inhabited by the parasite. The areas most commonly affected are cutaneous and lymphatic, but other body cavities can also be affected, such as the lungs. Currently, no form of filarial infection exists in the United States. Internationally, however, lymphatic filariasis affects 120 million people. In 2000, the World Health Organization (WHO) initiated the Global Alliance to Eliminate Lymphatic Filariasis, the goal of which is to eliminate this parasitic infection as a public health problem by 2020.


Causes

Lymphatic filariasis is caused by threadlike worms (nematodes) that live in the lymphatic system; it is transmitted by the bite of a mosquito carrying infective larvae. The larvae develop into adult worms in the lymphatic vessels, causing severe damage and swelling (lymphedema). The most common filarial species is Wuchereria bancrofti, but Brugia malayi and Brugia timri cause the infection in Asia. It takes several mosquito bites over many months to cause the infection. People living in tropical and subtropical settings are at the greatest risk for infection. Cutaneous filariasis caused by Loa loa is transmitted by the mango fly or deer fly; Onchocerca volvulus transmits microfilariae via the black fly; and Mansonella streptocerca transmits infection via a midge. Dirofilaria immitis may cause lesions in the lung periphery. Depending on the species, incubation may be 3 to 12 months.


Complications

Filarial infection can cause personal and socioeconomic hardships due to its debilitating consequences. Meningoencephalopathy and localized necrotizing granulomas are severe complications of L. loa infection. D. immitis may cause pulmonary infarction if the larvae lodge in the branches of the pulmonary arteries. Lymphatic filariasis may result in hydrocele or elephantiasis of the extremities or genitals. A secondary bacterial infection may cause elephantiasis, blindness, and infection of the skin and lymphatic system.


Assessment Findings

Assessment findings are based on the type of infection present and the body site affected. Signs and symptoms may be acute or chronic. Patients with lymphatic filariasis may be asymptomatic or may complain of fever and edema of the lymph system, commonly affecting the legs but also seen in the arms, breasts, and genitals. Thickening and hardening of the skin (elephantiasis) as well as skin exfoliation may occur. Filariasis affecting the pulmonary system causes a dry cough, dyspnea, wheezing, and anorexia. Cutaneous filariasis causes itching, subcutaneous lumps, localized pain, and lymphadenitis and may lead to ocular lesions and eye disorders such as glaucoma, optic atrophy, and corneal fibrosis.

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jul 20, 2016 | Posted by in INFECTIOUS DISEASE | Comments Off on Filariasis

Full access? Get Clinical Tree

Get Clinical Tree app for offline access